The present invention relates to the field of mass storage devices. More particularly, this invention relates to a disk drive which includes a device for controlling the pitch and roll attitudes of the sliders as they are loaded and unloaded from the surface of the disk in the disk drive.
One of the key components of any computer system is a place to store data. Computer systems have many different places where data can be stored. One common place for storing massive amounts of data in a computer system is on a disk drive. The most basic parts of a disk drive are a disk that is rotated, an actuator that moves a transducer to various locations over the disk, and electrical circuitry that is used to write and read data to and from the disk. The disk drive also includes circuitry for encoding data so that it can be successfully retrieved and written to the disk surface. A microprocessor controls most of the operations of the disk drive as well as passing the data back to the requesting computer and taking data from a requesting computer for storing to the disk.
The transducer is typically housed within a small ceramic block. The small ceramic block is passed over the disk in a transducing relationship with the disk. The transducer can be used to read information representing data from the disk or write information representing data to the disk. When the disk is operating, the disk is usually spinning at relatively high revolutions per minute (xe2x80x9cRPMxe2x80x9d). These days common rotational speeds are 7200 RPM. Rotational speeds in high performance disk drives are as high as 10,000 RPM. Higher rotational speeds are contemplated for the future. These high rotational speeds place the small ceramic block in high air speeds. The small ceramic block, also referred to as a slider, is usually aerodynamically designed so that it flies over the disk. The slider has an air bearing surface (xe2x80x9cABSxe2x80x9d) which includes rails and a cavity between the rails. The air bearing surface is that portion of the slider that is nearest the disk as the disk drive is operating. When the disk rotates, air is dragged between the rails and the disk surface causing pressure, which forces the head away from the disk. At the same time, the air rushing past the depression in the air bearing surface produces a negative pressure area at the depression. The negative pressure or suction counteracts the pressure produced at the rails. The different forces produced counteract and ultimately fly over the surface of the disk at a particular fly height. The fly height is the thickness of the air lubrication film or the distance between the disk surface and the head. This film eliminates the friction and resulting wear that would occur if the transducing head and disk were in mechanical contact during disk rotation.
The best performance of the disk drive results when the ceramic block is flown as closely to the surface of the disk as possible. Today""s small ceramic block or slider is designed to fly on a very thin layer of gas or air. In operation, the distance between the small ceramic block and the disk is very small. Currently xe2x80x9cflyxe2x80x9d heights are about 1-2 micro inches. In some disk drives, the ceramic block does not fly on a cushion of air but rather passes through a layer of lubricant on the disk. A flexure is attached to the load spring and to the slider. The flexure allows the slider to pitch and roll so that the slider can accommodate various differences in tolerance and remain in close proximity to the disk.
Information representative of data is stored on the surface of the memory disk. Disk drive systems read and write information stored on tracks on memory disks. Transducers, in the form of read/write heads attached to the sliders, located on both sides of the memory disk, read and write information on the memory disks when the transducers are accurately positioned over one of the designated tracks on the surface of the memory disk. The transducer is also said to be moved to a target track. As the memory disk spins and the read/write head is accurately positioned above a target track, the read/write head can store data onto a track by writing information representative of data onto the memory disk. Similarly, reading data on a memory disk is accomplished by positioning the read/write head above a target track and reading the stored material on the memory disk. To write on or read from different tracks, the read/write head is moved radially across the tracks to a selected target track. The data is divided or grouped together on the tracks. In some disk drives, the tracks are a multiplicity of concentric circular tracks. In other disk drives, a continuous spiral is one track on one side of a disk drive. Servo feedback information is used to accurately locate the transducer. The actuator assembly is moved to the required position and held very accurately during a read or write operation using the servo information.
One of the most critical times during the operation of a disk drive occurs just before the disk drive shuts down or during the initial moment when the disk drive starts. When shutdown occurs, the small ceramic block or slider is typically flying over the disk at a very low height. In the past, the small block or slider was moved to a non-data area of the disk where it literally landed and skidded to a stop. Problems arise in such a system. When disks were formed with a smooth surface, stiction forces occur between the slider and the disk surface. In some instances, the forces due to separate the slider from the suspension. Another problem is that landing a slider on the disk may limit the life of the disk drive. Each time the drive is turned off another contact start stop cycle occurs. After many contact start stop cycles, the small ceramic block or slider may chip or produce particles. The particles could eventually cause the disk drive to fail. When shutting down a disk drive, several steps are taken to help insure that the data on the disk is preserved. In general, the actuator assembly is moved so that the transducers do not land on the portion of the disk containing data. There are many ways to accomplish this. A ramp on the edge of the disk is one design method that has gained industry favor more recently. Disk drives with ramps are well known in the art. U.S. Pat. No. 4,933,785 issued to Morehouse et al. is one such design. Other disk drive designs having ramps therein are shown in U.S. Pat. Nos. 5,455,723, 5,235,482 and 5,034,837.
Typically, the ramp is positioned to the side of the disk. A portion of the ramp is positioned over the disk itself. In operation, before power is actually shut off, the actuator assembly moves the suspension, slider and transducer to a park position on the ramp. When the actuator assembly is moved to a position where parts of the suspension are positioned on the top of the ramp, the sliders or ceramic blocks do not contact the disk. Commonly, this procedure is referred to as unloading the heads. Unloading the heads helps to insure that data on the disk is preserved since, at times, unwanted contact between the slider and the disk results in data loss on the disk. The actuator assembly may be provided with a separate tang associated with each head suspension. The tang may ride up and down the ramp surface. In other drives, the ramp may be positioned such that the suspension rides up and down the ramp to unload and load the disk or disks of the disk drive. When starting up the disk drive, the process is reversed. That is to say that the suspension and slider are moved from the ramp onto the surface of the disk. This is referred to as loading the heads onto the disk.
During load and unload of the slider onto the disk, the slider typically rolls and pitches. Sometimes the slider pitches or rolls too much. The result is that the slider may then contact the disk. In other words, if the slider rolls too much when it is loaded or unloaded, the edge of the slider may contact the disk. If the slider pitches too much when the is loaded or unloaded, the front or back edge of the slider may contact the disk. Combinations of too much pitch and roll may cause the corners of the slider to contact the disk. Whenever the slider contacts the disk there is a possibility that the slider may damage the magnetic surface on the disk or that the slider may be damaged. Either event can result in loss of data. When the disk surface is damaged, such as by the slider gouging the surface of the disk, information stored at the gouge may be lost immediately. When the slider is damaged, such as by a portion of the slider coming off of the disk, the particles generated go into the drive and may eventually cause a head crash. The damage is greater at the higher rotational speeds of the disks in the disk drives. What is needed is a system and method for controlling the attitude of the slider in a disk drive. More specifically what is needed is a system for controlling the amount of pitch and roll of the slider. What is also needed is a system which is easy to manufacture and a system that also does not require adjustment. The system must also be rugged and stable over time. In other words, the system must be able to last for the life of the drive. The system must also be made of materials that will out gas to a minimum so that contaminants will not be added to the disk drive enclosure which could contaminant the lubricant on the disk. The system must also provide for easy rework and must also allow for gimballing of the slider with respect to the suspension.
There is still a further need for a system which eliminates or substantially reduces the moment produced on the slider by the electrical connection to the transducer. In addition, there is a need for systems which can be designed to allow a selected amount of stiffness in both the pitch and roll direction so that the slider is capable of adapting while passing over or flying over the disk.
An information handling system, such as a disk drive, includes a base, a disk stack rotatably attached to the base, and an actuator assembly movably attached to the base. The actuator assembly also includes a load spring and a slider attached to said load spring. A ramp is also attached to the base near the disk stack. The ramp is used to load and unload the sliders to and from the disk. The slider and load spring are attached to form a gimballing connection between the slider and the load spring. A motion limiting device is attached to either the slider or the load beam to limit the pitch and roll of the slider with respect to the load spring at the gimballing connection. The motion limiters can be added to the load spring or the slider or both. The motion limiters can be pieces of adhesive backed tape. The motion limiters can also be formed as features in the load spring or formed as features in the slider or can be formed as features in both the load spring and the slider. The slider attached to the load spring is also called a head gimbal assembly and the attachment of the slider to the load spring in a head gimbal assembly is also contemplated. The motion limiters limit roll and pitch attitudes at critical times in the operation of the disk drive, such as during the loading of the sliders to the disk from a ramp, and such as during the unloading of the sliders to the ramp from the disk.
Advantageously, during load and unload of the slider to and from the disk, the attitude of the slider is controlled along the pitch and roll axes to prevent the slider from contacting the disk. The motion limiters prevent slider roll during load and unload, so that the edge of the slider does not contact the disk. The motion limiters prevent slider pitch so that the front or back edge of the slider does not contact the disk during load and unload. The motion limiters also prevent the slider corners from contacting the disk. This lessens the possibility that the slider may damage the magnetic surface on the disk, or that the slider may be damaged, either of which can cause a head crash or other loss of data. The motion limiters control the attitude of the slider. In addition, higher rotational speeds can be used in the disk drives without having to worry about the increased risk of a head crash. The motion limiters control the amount of pitch and roll of the slider. The motion limiters are easy to manufacture and also do not require adjustment. The motion limiters are also be rugged and stable and last for the life of the drive. The motion limiters provide for easy rework and allow for gimballing of the slider with respect to the suspension.
An actuator assembly includes a stiff lead. A slider including at least one transducer is attached to the stiff lead. The slider also has at least one pad electrically connected to the transducer. A flexible joint apparatus is attached at one end to the lead and attached at the other end to the at least one pad of the slider. The flexible joint apparatus is made of an electrically conductive material. The flexible joint apparatus also includes a plurality of openings therein to form a waffle like structure. The structure is also called a cage structure. The flexible joint apparatus includes a bend between the one end attached to the lead and the other end attached to the pad of the slider. The bend allows for additional compliance in the connection between the slider and the lead so that different tolerances can be accommodated. The actuator assembly may also include a plurality of leads and a slider having a plurality of pads for electrically connecting to at least one transducer. A plurality of flexible joint apparatus can be used to attach each one of the plurality of leads to the plurality of pads of the slider. During manufacture, the plurality of flexible joint apparatus are attached to one another to prevent problems associated with electrostatic discharge. The attachment between the adjacent flexible joint apparatus is removed by laser ablation or some other means later in the manufacture.
Advantageously, the flexible joint system eliminates or substantially reduces the moment produced on the slider by the electrical connection to the transducer. The flexible joint system can also be designed to allow a selected amount of stiffness in both the pitch and roll direction so that the slider is capable of adapting while passing over or flying over the disk. The design can incorporate different openings to control the amount of stiffness in the pitch and roll directions. In addition, a bend can be used to further control the stiffness in the pitch and roll directions. Still a further advantage is that the flexible joints are made of an electrically conductive material so that the flexible joint not only provides mechanical flex between the stiff leads and the slider but also provides for the electrical connection between the slider and the stiff leads.